Because you can't change how a free person thinks nor can you force your view upon them. That's not how it works here in America. What we CAN do is teach to the next generation that race is merely the pigment of skin and nothing else. We MUST reinforce the belief that every Man, Woman and Child are created equal.

Think about it, without racism, all races could do the same thing... meaning white people can say the n word without the pass. So that’s why racism is legal. They pick our cotton and we don’t call them the n word. Fair trade

You better thank your lucky stars it isn’t, or else you and the rest of the Democrat party would be locked up. But to answer your question, “racism” is not illegal because the US Constitution guarantees the right to freedom of speech. Even if I don’t like what a racist has to say I’d still defend their right to say it to the death.